Common mental health disorder may triple risk for developing dementia, study finds

A new study provides another reason to address anxiety early, experts say. (ingwervanille/Moment RF/Getty Images via CNN Newsource)

As if people with anxiety don’t have enough to worry about, a new study is adding to that list  — suggesting the disorder may nearly triple the risk of developing dementia years later.

The research, to the authors’ knowledge, is the first to look into the association between different severities of anxiety and dementia risk over time, and the effect of the timing of anxiety on this risk, according to the study published Wednesday in the Journal of the American Geriatrics Society.

“Anxiety can now be considered a non-traditional risk factor for dementia,” said Dr. Kay Khaing, lead study author and a specialist geriatrician at Hunter New England Health in Newcastle, Australia, via email.

More than 55 million people worldwide have dementia, a number expected to increase to 139 million by 2050. With the condition also being a leading cause of death, researchers and health professionals have directed their focus toward prevention, particularly by addressing risk factors such as anxiety or lifestyle habits.

Previous studies exploring the relationship between anxiety and dementia have largely measured participants’ anxiety at one point in time, providing mixed conclusions — but how long someone’s anxiety lasts is an important aspect worth considering, the authors argued.

The team studied 2,132 participants recruited from the Newcastle-based Hunter Community Study between December 2004 and December 2007. They were ages 60 to 81 or older, and at the study’s start provided health data such as tobacco use or alcohol intake, or whether they had conditions such as hypertension or diabetes.

There were three assessments, also called waves, each five years apart. Researchers measured participants’ anxiety at the first and second assessments. Chronic anxiety was defined as having anxiety at both the first and second waves. Someone’s anxiety was considered resolved if they had anxiety only at the time of the first wave. New-onset anxiety refers to anxiety identified only at the second wave.

Dementia was identified using codes from the International Statistical Classification of Diseases, or pharmaceutical benefits data showing purchase of drugs for dementia, provided by the Australian Department of Health and Aged Care.

Ultimately, 64 participants developed dementia. Chronic and new anxiety were associated with a nearly thrice higher risk of dementia from any cause — with an average time to diagnosis of 10 years, the authors found.

Anxiety that resolved within the first five years was so unassociated with greater risk that the odds were similar to those without anxiety — a finding that Dr. Glen R. Finney, an American Academy of Neurology fellow, called “a welcome addition to our knowledge about anxiety and dementia.” Finney, director of the Geisinger Memory and Cognition Program in Pennsylvania, wasn’t involved in the study.

The results were also largely driven by participants under 70.

“We have known for a long time that stress increases risk for Alzheimer’s disease,” said Dr. Rudolph Tanzi, director of the McCance Center for Brain Health at Massachusetts General Hospital in Boston, who wasn’t involved in the study, via email. “This study agrees with earlier studies that therapy aimed at alleviating anxiety can help reduce risk for (Alzheimer’s disease). But, it’s the size of this study that is particularly compelling.”

The authors of the latest research did not have information on what helped some participants overcome their anxiety.

The findings highlight “the importance of addressing anxiety early and consistently,” said neurologist Dr. Joel Salinas, founder and chief medical officer of Isaac Health, a virtual and in-home clinical service for dementia and other brain health conditions. Salinas wasn’t involved in the research.

Stress and neurodegenerative disease

The study has a few limitations, including that measurements of participants’ anxiety were based on the four weeks before the assessments, the authors said. The team also lost 33% of participants who had a higher rate of anxiety at the beginning of the study; not knowing what ultimately happened to those people could result in an underestimate of the effect of anxiety on dementia.

“In the future,” Finney said, “having the findings followed up with a prospective study using cognitive measures and biologic measures of stress hormones, inflammation and neurodegeneration including for Alzheimer’s disease would be useful.”

The association between anxiety and dementia may be partly explained by the former’s link to vascular disease — a cause of dementia — and harmful effects on cells, experts said.

Stress increases cortisol in the brain and inflammation, and both kill nerve cells, said Tanzi, also the director of the genetics and aging research unit at Massachusetts General Hospital.

Anxiety is also associated with buildup of beta-amyloid, Khaing said, which is a hallmark sign of Alzheimer’s.

The disorder has also been linked with structural brain changes “such as brain and hippocampal atrophy, all processes which are also associated with dementia,” Khaing added. Atrophy refers to the wasting away of a tissue or organ, especially as a result of cell degeneration.

However, the study “might also suggest the possibility that anxiety may be an early manifestation of underlying brain disease,” Salinas, clinical assistant professor of neurology at NYU Langone Health, said via email. “Someone’s early cognitive decline may contribute to someone’s anxiety (e.g., making mistakes or being embarrassed in social situations).”

At the beginning of the study, the authors excluded people who already had cognitive impairment, but they acknowledged that undetected decline is still possible.

People with anxiety are also more likely to make unhealthy choices, such as having a poor diet or smoking, the authors said.

Managing anxiety

Anxiety is a normal response to stressors, but if it’s excessive, “please seek help,” Khaing said.

Talk with your doctor or a mental health professional about your options, which can include lifestyle changes such as stress management, healthy diet, exercise and better sleep, all of which also separately influence your dementia risk, experts said. Important forms of treatment also include different types of therapy or antidepressant medications.

“But I recommend avoiding certain brain-impairing medications including tricyclic antidepressants, benzodiazepines and strong antihistamines,” Finney said.

Cognitive behavioural therapy is the treatment of choice for many anxiety disorders. It works by uncovering “unhealthy patterns of thought and how they may be causing self-destructive behaviours and beliefs,” according to the National Alliance on Mental Illness.

Additionally, “try to take on a meditation practice and limit the expectations from others and yourself to respond to emails, texts and social media,” Tanzi said. “We also recommend avoiding people you really dislike and interacting with those who have a positive effect … on your well-being.”

Tanzi stressed that anxiety is a result of our brain’s “oldest and more primitive parts” being aimed only at survival.

“It is important to always try to be mindful and self aware of whether your brain is bullying you to over-emphasize those survival needs,” he said.